Firefox may have been overshadowed by Chrome in terms of worldwide users, but it is still an excellent browser, even on Android. The latest update, version 49, has the usual dose of new features and bug fixes.
The biggest new few feature is offline page viewing, which coincidentally enough, was recently added to the Chrome Dev builds. However, Chrome allows you to manually choose what pages you want stored for offline reading, whereas Firefox tries to store recent pages offline automatically. I imagine it wouldn't be too difficult to implement Chrome's offline functionality, now that the framework is in place.
Firefox 49 includes an updated Firefox Login Manager, which allows user info (including passwords) from HTTP sites to be used on HTTPS versions of the same site. This greasily helps sites transitioning to HTTPS, as all of their users' saved information would still be remembered.
Finally there is a number of improvements to tabs. The scroll position in tabs is now always remembered, media controls have been updated to avoid sounds playing from multiple tabs, and outdated tabs are now hidden if the "Always restore tabs" setting is enabled.
You can get Firefox 49 from the Play Store with the handy widget below or from APKMirror.